Small loop antennas

This chapter examines the basic theory of small loop antennas, and provides an overview of some practical construction methods. The small loop antenna is almost ideal for DXing the crowded AM broadcast band and low frequency “tropical” bands. These antennas are fundamentally different from the large loop types, and are very often the antenna of choice for low frequency work. The differences between small loops and large loops show up in some interesting ways, but perhaps the most striking are the directions of maximum response—the main lobes—and the directions of the nulls. The nulls of a loop antenna are very sharp and very deep. Small changes of pointing direction can make a profound difference in the response of the antenna. A wire loop antenna is made by winding a large coil of wire, consisting of one or more turns, on some sort of frame. The shape of the loop can be circular, square, triangular, hexagonal, or octagonal. For practical reasons, the square loop seems to be most popular.